Related Articles

The year-long, double-blind study of 225 men was led by Stephen Bent, MD, a staff physician at the San Francisco VA Medical Center, and Andrew Avins, MD, MPH, of the Northern California Kaiser Permanente Division of Research.

The results are published in the February 9, 2006 issue of the New England Journal of Medicine.

In their study, the researchers randomly assigned patients with enlargement of the prostate, also known as or benign prostate hyperplasia or BPH, to take either saw palmetto or a placebo twice a day for one year. Subjects returned at regular intervals to be assessed for symptoms and side effects. Symptoms were assessed according to a standard symptom score for BPH and objective measures of urinary function.

"If you look at the change in symptoms over time between the two groups, it was almost identical," reports Bent, who is also an assistant professor of medicine at the University of California, San Francisco. "There was no statistically significant difference at any time point during the study."

The researchers also looked at subgroups of patients -- those with more and less severe symptoms and those with larger and smaller prostates -- and found no difference in any of the subgroups between the herbal extract and placebo.

"The results of this study clearly do not support a strong clinical benefit of saw palmetto for BPH," concludes Bent. "However, whether other doses, formulations, or patient populations might respond differently is unknown."

The researchers estimate that saw palmetto is used by over two million men in the United States for treatment of BPH, which is said by the National Institutes of Health to affect more than 50 percent of men over 60 and upwards of 90 percent of men over 70.

Bent acknowledges that the study results are surprising, since many earlier studies concluded that saw palmetto is effective against BPH. However, he points out a number of differences between the current study and earlier research.

"Prior studies were generally small in size and short in duration," he says. "Plus, the vast majority of them did not use the standard symptom score that we used for assessing the severity of BPH," which is now commonly used to judge the efficacy of pharmaceutical drugs for treatment of the condition.

Another potential problem with earlier studies has to do with the nature of saw palmetto itself, according to Bent. "This is a very pungent herb, and it took our research team a long time to create a placebo that convincingly duplicates its strong smell and taste. We suspect that prior trials didn't adequately address that problem." As a result, he says, "it's possible that some of the positive findings in earlier work may be due to the fact that the blinding wasn't adequate." In other words, patients in those studies knew whether they were taking the herb or the placebo, and "someone who's taking something that's smelly and likely to be the plant extract is perhaps more likely to report a benefit than someone who's taking an odorless and tasteless tablet."

At the end of the current study, 40 percent of patients in the saw palmetto group believed they were taking the herbal extract versus 46 percent in the placebo group, demonstrating that the blinding was adequate, says Bent.

Bent notes that his research team took pains to select an herbal product that matched the levels of fatty acids and sterols -- commonly believed to be saw palmetto's active ingredients -- found in most commonly available commercial preparations of the herb.

Almost all prior studies of saw palmetto used exactly the same dose, says Bent -- 160 milligrams twice a day -- and the current study used that dose as well. He notes that such consistency of dose is not typical among studies of most other herbal medications.

The current study subjects reported no statistically significant side effects from saw palmetto.

Bent cautions that while the study is strongly indicative, it is not conclusive. "This is a surprising finding that contradicts the weight of prior evidence," he observes. "There is good reason for other researchers to conduct another study to validate these results, taking care that blinding is done carefully once again."

In addition, says Bent, "Some people believe that higher doses may be potentially effective, and that's an area that we did not address."

A major new NIH-funded study of saw palmetto and another commonly-used herbal treatment for BPH is currently in the final planning stages, according to Avins, who is a co-author of the current study. The new study will involve several hundred patients at 11 centers nationwide, and researchers hope it will shed more definitive light on the questions of adequate doses and other potentially useful natural treatments for BPH, says Avins.

Other co-authors of the current study include Christopher Kane, MD, and Katsuto Shinohara, MD, of SFVAMC; John Neuhaus, PhD, and Esther S. Hudes, PhD, MPH, of UCSF; and Harley Goldberg, DO, of UCSF and KPNC.

###

The study was funded by a grant from NIH that was administered by the Northern California Institute for Research and Education.

University of California - San Francisco. "Saw palmetto no better than placebo for enlarged prostate, study finds." ScienceDaily. ScienceDaily, 13 February 2006. <www.sciencedaily.com/releases/2006/02/060213102419.htm>.

University of California - San Francisco. (2006, February 13). Saw palmetto no better than placebo for enlarged prostate, study finds. ScienceDaily. Retrieved March 3, 2015 from www.sciencedaily.com/releases/2006/02/060213102419.htm

University of California - San Francisco. "Saw palmetto no better than placebo for enlarged prostate, study finds." ScienceDaily. www.sciencedaily.com/releases/2006/02/060213102419.htm (accessed March 3, 2015).

More From ScienceDaily

More Health & Medicine News

Featured Research

Mar. 3, 2015 — Why do people shake hands? A new study suggests one of the reasons for this ancient custom may be to check out each other's odors. Even if we are not consciously aware of this, handshaking may ... full story

Mar. 3, 2015 — Doctors write millions of prescriptions a year for drugs to calm the behavior of people with Alzheimer’s disease and other types of dementia. But non-drug approaches actually work better, and carry ... full story

Mar. 3, 2015 — Briefly counseling college students on the dangers of binge drinking is effective in lowering heavy drinking levels among many students, but only temporarily. Three out of four will be right back ... full story

Mar. 3, 2015 — Body mass index in healthy adolescents has a statistically significant association with both systolic blood pressures and diastolic blood pressures, research shows, and it highlights the significance ... full story

Mar. 3, 2015 — Loneliness brought about by the death of a spouse can trigger a wider network of depression-like symptoms, a study has found, but authors suggest that doctors are often too quick to attribute these ... full story

Mar. 3, 2015 — Family Based Interpersonal Psychotherapy (FB-IPT) is more effective in treating preadolescent children with depression compared to child-centered therapy (CCT), a recent study has found. ... full story

Mar. 3, 2015 — Two of the four known groups of human AIDS viruses (HIV-1 groups O and P) have originated in western lowland gorillas, according to new research. The scientists conducted a comprehensive survey of ... full story

Mar. 3, 2015 — Scientists have succeeded in producing cartilage formed from embryonic stem cells that could in future be used to treat the painful joint condition osteoarthritis. With their huge capacity to ... full story

Mar. 3, 2015 — Everyone worries about losing their memory as they grow older—memory loss remains one of the most common complaints of the elderly. But the molecular reasons behind the processes remain unclear, ... full story

Featured Videos

Mom Triumphs Over Tragedy, Helps Other Families

AP (Mar. 3, 2015) — After her son, Dax, died from a rare form of leukemia, Julie Locke decided to give back to the doctors at St. Jude Children&apos;s Research Hospital who tried to save his life. She raised $1.6M to help other patients and their families. (March 3)
Video provided by AP

Woman Convicted of Poisoning Son

AP (Mar. 3, 2015) — A woman who blogged for years about her son&apos;s constant health woes was convicted Monday of poisoning him to death by force-feeding heavy concentrations of sodium through his stomach tube. (March 3)
Video provided by AP

Sep. 27, 2011 — Men with urinary problems related to an enlarged prostate who received increasing doses of the fruit extract saw palmetto did not experience a reduction in these symptoms compared to men who received ... full story

Sep. 27, 2011 — Long-term adminstration of the dietary supplement saw palmetto, even at three times the usual dose, did not reduce symptoms of prostate enlargement significantly better than placebo in a large group ... full story

ScienceDaily features breaking news and videos about the latest discoveries in health, technology, the environment, and more -- from major news services and leading universities, scientific journals, and research organizations.